package com.example.test.a20240530;

import java.util.HashSet;
import java.util.Scanner;

public class HJ10字符个数 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.next();
        HashSet<Character> hs = new HashSet<>();
        for (int i = 0; i < str.length(); i++)
            hs.add(str.charAt(i));
        System.out.println(hs.size());
    }
}
